[en] A systematic evaluation of adsorbents for potential use in the /sup 191/Os//sup 191m/Ir medical radionuclide generator included 39 inorganic materials broadly classified as a. oxides (9), b. antimonates (7), c. ferro-ferricyanides (8), d. phosphates (6), e. sulfides (3), f. and other materials (6), including the organic anion-exchanger AGMP-1. The goal of these studies was to develop a new generator system that will have a long useful shelf-life, good iridium-191m yields, low osmium-191 breakthrough and eliminate the need for a scavenger column. The uptake of /sup 190/Os in oxidation states (VI), potassium osmate, K/sub 2/[OsO/sub 2/(OH)/sub 4/]; (IV), potassium-hexachloroosmate, K/sub 2/OsCl/sub 6/; and (III), hexathiocyanoosmate, K/sub 3/Os(SCN)/sub 6/, was measured. The adsorbents having a high /sup 191/Os uptake were evaluated for /sup 191m/Ir elution yield using three physiologically compatible eluents. Although many exchangers showed good Os(III), (IV) or (VI) uptake in the ''batch'' equilibration studies, they showed only low /sup 191m/Ir elution yields. Only AGMP-1 showed significant /sup 191m/Ir elution yields under the test conditions. Research sponsored by the Office of Heallth and Environmental Research, US Department of Energy, under contract W-7405-ENG-26 with the Union Carbide Corporation